Northeast Brazil is at the centre of attention as the spreading of the Zika virus was recently declared a public health emergency of international concern. Over the last three months, over 4,000 cases of new-borns with microcephaly have been reported in Brazil, compared to only 147 in the whole year of 2014. Eighty-six percent of these cases are found in Northeast Brazil.

Northeast Brazil is known as the most impoverished region in the country, and although Zika is spreading across the continent, affecting wealthier regions as well, the question arises: is the poorer population especially vulnerable to the epidemic, and if so, why?

Journalist Clare Wenham (2015) recently asserted in The Guardian: “Zika is a disease of poverty, similar to other neglected tropical diseases such as chikungunya and dengue”. All three diseases–Zika, dengue and chikungunya—are transmitted by Aedes mosquitoes. Therefore, epidemiological data on dengue lends itself to drawing conclusions about the spread of the Zika virus.

However, although dengue is on the WHO list of neglected tropical diseases, the epidemiological association between infection and poverty is not so clear. In 2015, Kate Mulligan et al. (2015) published a systematic review which argued that, “while poverty has long been considered a determinant of dengue, the research evidence for such a relationship is not well established” (p. 10).

So can we then assume that the association with poverty would be similarly unclear in the case of Zika? If we only looked at acute infections, with rash and mild fever, this might indeed be the case. However, in the case of Zika-associated microcephaly, I argue, we have reason to expect a stronger correlation with poor living conditions. The crux in the case of Zika is that prevention is much more difficult for pregnant women in impoverished communities than in wealthier settings. A look at the recommended measures of prevention can explain why.

First, the Brazilian government advises women to postpone pregnancy for several months until the crisis is over. But this implies that pregnancies are planned and that women have access to and control over contraception. Women and adolescent girls in deprived areas are more at risk of unplanned pregnancies compared to women with a more stable social background and better education. In the state of Bahia where I lived in Northeast Brazil, one in five children are born to a teenage girl. Moreover, the fear of Zika might also increase illegal, unsafe abortions.

Second, vector control aims at the elimination of water containers where Aedes larvae develop. In the so-called condomínios, gated communities, janitors and cleaners help removing mosquito breeding sites. But in poorer neighbourhoods or favelas, where litter is often abundant and water is trapped in cracks, holes, and blocked drains, vector control is much harder to achieve.

Third, people are advised to keep mosquitoes out of their houses, which is facilitated in buildings with air-conditioning. In poorer areas, however, houses require open windows for ventilation and light, and oftentimes windows are just holes in the wall with wooden shutters (see below). Keeping the windows closed during the day is hardly possible.

Houses in the city of Salvador, Bahia, Northeast Brazil (Photo: Lesshafft 2014)

Fourth, pregnant women should try to stay indoors, especially during the first trimester when the nervous system of the child is developing. While this would be possible for a pregnant woman who has an air-conditioned home, car, and workplace, or who can stay off work altogether, women in poorer neighbourhoods with less comfortable homes would spend a lot of their time outside where they are at higher risk of infection.

Finally, it is recommended that pregnant women wear long sleeves and use insect repellent. Again, because of their air-conditioned environment, better-off women often wear long sleeves and trousers anyway, but the women I knew in poorer settings were used to wearing sleeveless shirts and very short skirts or shorts. Also, insect repellent was not readily available in local supermarkets. With the recent price rise of up to three or four times of the normal price in the region, repellents would also add to the financial burden in low-income settings.

In conclusion, a look at the unequal living conditions in Northeast Brazil and the lack of safe spaces for pregnant women in impoverished communities gives reason to think that Zika-related birth defects will hit the poor hardest. Not to mention the difficulty in raising a disabled child in poverty.